CAN COMMUNICATION SYSTEM Engine Stop and Start ECU Communication Stop Mode

DESCRIPTION

Detection Item Symptom Trouble Area
Engine Stop and Start ECU Communication Stop Mode

Either condition is met:


  • Communication stop for "Stop and Go/Start" is indicated on the "Communication Bus Check" screen of the GTS.

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  • Communication system DTCs (DTCs that start with U) that correspond to "Engine Stop and Start ECU Communication Stop Mode" in "DTC Combination Table" are output.

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  • Engine stop and start ECU branch line or connector

  • Power source circuit of engine stop and start ECU

  • Engine stop and start ECU ground circuit

  • Engine stop and start ECU

WIRING DIAGRAM

B003WW2E02

CAUTION / NOTICE / HINT

Note


  • Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output.

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  • Before measuring the resistance of the CAN bus, turn the engine switch off and leave the vehicle for 1 minute or more without operating the key or any switches, or opening or closing the doors. After that, disconnect the cable from the negative (-) battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.

  • After turning the engine switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) battery terminal notices before proceeding with work.

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  • After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.

    DTC check procedure: Drive the vehicle at a speed of 30 km/h (19 mph) or more for 20 seconds or more.

  • After the repair, perform the CAN bus check and check that all the ECUs and sensors connected to the CAN communication system are displayed as normal.

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  • Inspect the fuses for circuits related to this system before performing the following procedure.

Tech Tips


  • Before disconnecting related connectors for inspection, push in on each connector body to check that the connector is not loose or disconnected.

  • When a connector is disconnected, check that the terminals and connector body are not cracked, deformed or corroded.

PROCEDURE


  1. CHECK FOR OPEN IN CAN BUS LINES (ENGINE STOP AND START ECU BRANCH LINE)


    1. Disconnect the cable from the negative (-) battery terminal.

    2. B003W3EC15
      *a

      Front view of wire harness connector

      (to Engine Stop and Start ECU)

      Disconnect the K139 engine stop and start ECU connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      K139-13 (CANH) - K139-14 (CANL) Cable disconnected from negative (-) battery terminal 54 to 69 Ω
      Result
      Result
      OK
      NG

    NG

    REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (ENGINE STOP AND START ECU)

    OK

  2. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)


    1. Disconnect the A93 engine stop and start ECU connector.

    2. B003WJQC05
      *a

      Front view of wire harness connector

      (to Engine Stop and Start ECU)

      Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A93-8 (GND1) -Body ground Cable disconnected from negative (-) battery terminal Below 1 Ω

    3. Reconnect the cable to the negative (-) battery terminal.

    4. B003VDGC13
      *a

      Front view of wire harness connector

      (to Engine Stop and Start ECU)

      Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      A93-3 (BIN1) - Body ground Always 11 to 14 V
      K139-18 (IG2) - Body ground Engine switch on (IG) 11 to 14 V
      K139-19 (ACC) - Body ground Engine switch on (ACC) 11 to 14 V
      K139-21 (IG1) - Body ground Engine switch on (IG) 11 to 14 V
      Result
      Result
      OK
      NG

    OK

    REPLACE ENGINE STOP AND START ECU Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)